Without knowing how far away the hives will be and how defensive your bees are, it is impossible to offer a suggestion.
Unless it is a party for beekeepers, within a crowd of 100 people odds are there is at least one person who is afraid of bees and will raise a stink if they see a hive nearby.
Here's my backyard, in glorious iPhone 3D view:
The vertical scale is exaggerated, but it's a decent representation. Just above the Bees is a steep slope (dark green) planted heavily with morning glory, and then there's a 3' high wood fence that's shown as the thin wavy line. The thicker white line leading away from People is a brick path.
The tables and grill will up on the upper level where it says "People." The guests will walk down the steps and path into the garden to pick the corn. The hive is about 35' from the steps, and I'll have some signs and/or potted plants as a barrier to keep people from visiting the hive.
The hive is about 40+', as the bee flies

, to the tables, but it's also 15' below that level, and the hive entrance faces the garden, so most of the bee flow is towards the garden. I always have bees buzzing around in the garden, but that would be true whether the hive was mine or not, or in my yard or not. Bees just like squash flowers, and most of the garden is a pumpkin patch right now (I'm going to have the same situation in late October

).
Regarding my bees, they're about medium tempered. I often get stung once or twice when I work the hive, usually through my $35 gloves

, or during the 10 minutes afterward if I take off my suit without checking first. I often have 2-3 bees follow me away from the hive after I close it up, but I never have a cloud of them.
I almost never get stung if I'm in the garden or backyard and it's not within 10 minutes of me working the hive.
My newbee guess is that I won't actually have a problem, but then again perception counts for something, and I don't want my guests freaked out by my bees, especially since there will be lots of children involved.
Yes, we're in a pretty severe dearth right now. I just put a couple quarts of syrup in the hive this morning; we'll see how much they drink over the next day or two.